Dynamics of the soil chemical properties in shifting cultivation systems in the tropics: a meta-analysis

Abstract

The forest cultivation system (slash-and-burn or shifting cultivation) has contributed to the transformation of social systems since the early Neolithic period. Despite being considered by conservationists and public policy makers as a system of low productivity that generates environmental degradation and contributes to the maintenance of rural poverty, the shifting cultivation system (SCS) is being declared a practice that is highly ecologically and economically efficient. This dichotomy of opinions is present in the studies on the effects of the SCS on the soils of rainforests. To circumvent this inconsistency, we used a systematized review method, the meta-analysis, with the objective of integrating and synthesizing the data published in the literature to assess the sustainability of the SCS. Four variables directly related to the properties of the soil were chosen for the meta-analysis: pH, CEC, Total C and Total N. Among the overall magnitude values obtained, only the one for the pH was positive. The study showed that the SCS has no impact on the CEC. The total positive magnitude obtained for the pH variable shows that the SCS makes the stability of the pedologic conditions possible guaranteeing the maintenance of the soil/vegetation complex of rainforests. The results obtained for the other variables, despite having negative or null total magnitudes, did not refute the conclusions reached with the pH variable. These results corroborated the position taken by the groups that defend the SCS as a viable alternative for the biological conservation of rainforest biomes, coexisting with preservation areas and other traditional activities in diversified rural scenarios.